Duplex packaging material and method of making same



April 23, 1964 w. E. ANDERSON ETAL 3,130,647

DUPLEX PACKAGING MATERIAL AND METHOD OF MAKING SAME I 4 Sheets-Sheet 1 Filed Sept. 10, 1957 FIG. 2

INVENTORS WILLIAM E. ANDERSON RALPH WILLIAM SCHLIENZ CLARENCE PHILIP FRILING I BY J fmfM M aWf Av,

ATTORNEY? April 28, 1964 w. E. ANDERSON ETAL 3,130,647

DUPLEX PACKAGING MATERIAL AND METHOD OF MAKING SAME 4 Sheets-Sheet 2 Filed Sept. 10, 1957 INVEN WILLIAM E. ANDER H WILLIAM SC CLARENCE'PI'IILIP F TORS SON v I R HLIENZ 7 RILING I V v v mmgd 74Zm/MZ7 ATToiiN El s Aprll 23, 1964 w. E. ANDERSON ETAL 3,130,647

DUPLEX PACKAGING MATERIAL AND METHOD OF MAKING SAME Filed Sept. 10, 1957 4 Sheets-Sheet 3 INVENTORS WILLIAM E. ANDERSON RALPH WILLIAM SCHLIENZ CLARENCE PHILIP FRILING BY 7 W, W mi, @M'%@ ATTORNEYS P 1964 w. E. ANDERSON ETAL 3,130,647

DUPLEX PACKAGING MATERIAL AND METHOD OF MAKING SAME Filed Sept. 10, 1957 4 Sheets-Sheet 4 INVENTORS WILLIAM E. ANDERSON RA WILLIAM SCHLIENZ CL R NCE PHILIP FR LI'NG ATTO R N EYS United States Patent DEJFLEX PA-ACKAGING MATERIAL AND METHUD 6T3 lvilfiu w lg SAME Viinam E. Andersen, Bloomsbury, Ralph William Scn-ienz, Hillaale, md Ciarence Philip Friiing, Milf rd, lallfi, rs to illegal laper Qorporarzon, New

1 rk, N.Y., a corp-oration Delaware Filed Sept. 19, 1957, Ser. No. 683,168 2 lain1s. (81. 9335) The present invention relates, generally, to the packaging art, and more specifically to novel and improved packing materials, and to improved arrangements for making and using the same, and to improved products incorporating the same.

One of the general features of the invention resides in the provision of a new product or article of manuiacture, which comprises a plurality of layers of web material loosely bonded together at widely spaced points. The loose-bonded, muiti-layer web is advantageously utilized in such end products as bags, for example, whereby in substantial effect, the layers of the bag are separate and independent. in dis respect, it has been discovered that where the Several layers of a multi-layer bag are structurally separate the strength of the bag is greatly increased over similar bags Where the layers are laminated, glued or otherwise bonded over substantial areas. T iis is particularly true where one or more of the layers have resilient characteristics while one or more of the other layers are largely non-resilient.

In accordance with the above, it is one of the more specific features of the invention to provide a new product or article of manufacture, in the form of a loose-bonded, rnulti-layer web material, in which one or more of the layers or webs is a material having resilient characteristics and another of the webs is substantially non-resilient. The various webs are bonded together at widely spaced areas of limited size, and not to a substantially greater extent than is necessary to facilitate handling of the multilayer web prior to and during the making of bags and other products therefrom.

In one specific form of the invention, the new product takes the form of a bag or the like, or loose-bonded, multilayer web mat rial for making a bag or the like, and, advantageonsly, the several layers forming the web material are bonded or secured together at points or along lines which, in the finished bag or other end product, lie along and are substantially or entirely included by the seams of the bag. Accordingly, while the several layers of material are secured along the seam of the bag or end product, the layers are elsewhere free from each other or substantially so, whereby desirable and advantageous characteristics are obtained.

A further specific feature of the invention resides in the provision of a loose-bonded, multi-layer web material, having general characteristics as set forth above, in which at least one of the layers or webs is formed of heat-sealable material having properties adapting to be loosely bonded to one or more other webs by partial heat sealing and adapting it to be subsequently further heat sealed, as in the making of a bag, for example. Complementary to the foregoing specific feature, it is a further specific feature of the invention to provide a bag or other end product, formed of web material including a web loosely bonded by partial heat sealing, wherein one or more seams of the end product are substantially inclusive of or coextensive with the partially heat sealed areas, and such seams are formed by heat sealing. In accordance with this aspect of the invention, a completely sealed bag or container may be provided wherein the several layers of material are structurally separate, except for limited areas along the seams of the container.

In another specific form of the invention, a loosebonded, multi-layer web material and/ or an intermediate or end product made therefrom, is provided, in which one of the layers of the web material is substantially nonindependently handleable. The arrangement is such that the non-independently handleable web or layer is loosely bonded to an independently handleable carrier web, in a manner permitting realization of the various advantages heretofore described, while at the same time permitting various handling and manipulative operations to be carried out without damaging the non-independently handleable web. It will be understood, in this respect, that the term non-independently handleable, as used herein, is not used in the strictly literal sense, to mean that a web cannot, under any circumstances be independently handled. Rather, the term is intended to convey the meaning that the web is relatively fragile or breakable, or easily damageable, so that, if extensively handled or manipulated by itself, would be likely to be damaged, unless substantial precautions were taken.

Other aspects of the invention reside in various improved methods of an apparatus for making the various products mentioned above, and in other intermediate or end products which have novel and improved features characteristic of the loose-bonded, multi-layer construction of the invention.

For a better understanding of the invention, reference should be made to the following detailed description and the accompanying drawings, in which:

FIG. 1 is a simplified schematic view of an improved apparatus having features especially adapted for making one or more of the products of the invention, in accordance with a method of the invention;

FIG. 2 is a perspective view of a loose-bonded, multilayer web material made in accordance with the invention;

FIG. 3 is an enlarged cross sectional view taken on line 33 of FIG. 2;

FIG. 4 is a perspective view of an improved bag formed with a web material of the type shown in FIG. 2;

FIG. 5 is an enlarged cross sectional view taken on line 55 of FIG. 4;

FIGS. 6 and 7 are cross sectional views of alternative forms of pressure rolls which may be advantageously incorporated in the apparatus of FIG. 1;

PEG. 8 is a front elevation of a modified form of pressure roll which may be used to advantage where one of the webs of the multi-layer web material has an opening therein;

FIGS. 9 and 10 illustrate alternative arrangements for making loose-bonded, multi-layer web material where one of the webs is formed of heat-scalable material;

FIG. 11 illustrates an arrangement for making loosebonded, multi-layer web material, wherein a composition is applied to selected portions of one web to prevent bonding of the webs over such areas;

FIG. 12 illustrates an arrangement for making loosebonded, multi-layer web material wherein an adhesive composition is applied to selected areas of one of the webs;

FIG. 13 is a schematic illustration of an apparatus for making bags or the like with loose-bonded, multilayer web material of the invention; and

FIG. 14 is an apparatus similar to that of FIG. 1, incorporating alternative arrangement for making loosebonded, multi-layer web material.

Referring now to the drawings, and initially to FIG. 1 thereof, the numeral 10 designates an apparatus for extruding a web of heat-scalable plastic material, such as polyethylene, for example. The extruder 10 may be of more or less conventional design, but advantageously includes a suitable heating means 11 controlled by a thermostat 12 adapted to maintain the temperature of the material in the extruder at about 650 F. In this respect, the normal extrusion temperature for polyethylene and like materials may be in the order of 300 F. However, in accordance with one aspect of the present invention, the material may be extruded at a substantially higher temperature, with the result that the areas of the material may be twice subjected to heat sealing, as will be more fully explained.

At the bottom of the extruder is a suitable slit, through which a web 13 of plastic material may be extruded; and in some, though not necessarily all, forms of the invention, the dimensions of the slit may be such as to eifect the extrusion of a web having a thickness not substantially greater than one mil.

Directly below the extruder 1d are opposed rollers 14, 15, forming a roll nip into which the extruded web 13 is directed. In accordance with one specific aspect of the invention, the roller may be formed of metal and is provided with means, such as an internal cavity 16, for receiving a cooling medium, while the roller 14 is formed of resilient material, such as rubber, and is arranged to apply pressure against the roller 15 in limited areas. Thus, the roller 14 is advantageously provided with a plurality of portions 17 of narrow width and of greater diameter than the body of the roller. In one form of the invention it is contemplated that the increased diameter portions 17, which may be considered pressure surfaces, may be provided at or adjacent each end of the roller 14 and also at one or more places intermediate the ends thereof. By way of example, the pressure surfaces may be in the order of /2" to A" wide, and about 0.010-0.012" in thickness.

As shown in FIGS. 6 and 7, the pressure surfaces 17 may be formed integrally with the body 18 of the roll, or they may be formed by providing a cylindrical body 19 with one or more wraps of tape 20, such as pressuresensitive polytetrafluroethylene.

Referring again to FIG. 1, a web 21 of material, such as kraft or other paper, cellophane, polyethylene terephthalate, metal foil, cloth, or the like is drawn from a supply 22 thereof and passed over the roller 14 and through the roll nip. Advantageously, the web 21 is of an independently handleable nature, in that it may be handled by itself without excessive risk of breakage or damage.

As the web 21 passes over the roller 14, it is brought into flat contact with the descending web 13 of extruded plastic material. The two webs 21, 13 move into flat, contacting relation, and then move together through the roll nip, the exposed surface of the extruded web being in contact with the chilled metal roller 15.

When the webs pass through the nip, pressure is applied to widely spaced areas of limited size, by the pressure surfaces 17, whereby to effect a partial heat-seal bond between the webs. In this respect, the term partial heat-seal bond is not necessarily intended to signify any lacking in quality or completness of the bond, but is intended to signify that further heat sealing of the same areas may be accomplished at a later stage. The webs thus bonded together travel around a portion of the roller 15, over an idler 23, and to a suitable wind-up device 24, which forms the multilayer web material 25 into a roll 26.

In accordance with the invention, the separate webs of the 'multi-layer web material are bonded together at widely spaced areas of limited size, so that the multilayer material may be characterized as loose-bonded. Thus, multi-layer web material formed with the apparatus and in accordance with the method illustrated in FIG. 1 is bonded along spaced longitudinally extending strips 27-29 (FIG. 2) of narrow width, the strips 27, 29 being 'at the opposite marginal edges of the web 25, while the strip 28 is near the center thereof. It will be understood, however, in this respect, that the separate webs need not 4 be bonded along continuous or longitudinal strips, but may be bonded at spaced spots, or along transversely or otherwise disposed lines, as may best suit the intended use of the material.

In accordance with one aspect of the invention, the material forming one of the webs, usually the extruded web 13, is of a resilient nature, such materials as poly ethylene, styrene, nylon, vinylidene and chloride fluorocarbon plastic being representative, but not exclusive. A loose bonded, multi-layer web material having at least one resilient web has many advantageous features, and is particularly advantageous in connection with the making of bags or the like, where the bag is provided with an outer layer of paper, foil, cellophane or the like, which is of a relatively non-resilient nature. Thus, a bag having a loose-bonded, resilient layer exhibits markedly greater useful strength than a bag formed of similar materials, in which the layers are completely or substantially bonded together, as is a conventional practice.

Where the resilient web material is polyethylene or the like, as before mentioned, further advantages accrue, in that the material is not only resilient, but is also heat-sealable. But in this respect, the invention contemplates, also, that, in a loose-bonded, multi-layer Web material, one of the webs may be of a resilient material and another of a heat-scalable material; but, in proper cases either or both characteristics of resiliency and heatsealability may be eliminated, as will be further described.

In accordance with another specific aspect of the invention, one of the webs, and, again, usually the extruded web 13, may be of minimum thickness, so as to be characterized as non-independently handleable, in that it would, by itself, require careful handling to avoid damage. In the method of FIG. 1, the web 13 may be made non-independently handleable by sufilciently reducing the width of the extrusion opening, so that the thickness of the extruded web is not substantially greater than one mil, for example. The non-independently handleable web is drawn directly from the supply thereof, which is, in this case, the extruder 14), and brought into fiat contact with a carrier web, which is advantage ously, though not necessarily, independently handleable. The webs are then loose-bonded to form a multi-layer web material, which may be readily handled and shipped for subsequent use in the manner desired.

One of the most advantageous uses of the new loosebonded, multi-layer web material is in the making of bags or the like, substantially as shown in FIGS. 4 and 5. To this end, sections of the multi-layer web material may be folded over and overlapped along longitudinal marginal edge portions. Advantageously, though not necessarily, the outer layer of the web material is a suitable paper, while the inner layer is a heat-sealable material, such as polyethylene. When longitudinal edge portions 30, 31 are overlapped, as shown in FIG. 5, the overlapped portions may be heat sealed to complete a tubular structure, in which the inner layer 32 is substantially entirely structurally independent from the outer layer 33, to form a loose-bonded, multi-layer bag. Eventually, the bag may be closed at its top and bottom, as shown at 34 in FIG. 4, for example.

Advantageously, the web material utilized in making a bag of the type shown in FIGS. 4 and 5 is formed of layers which are loose-bonded, by heat sealing or otherwise, only along marginal edge portions. Accordingly, in the completed bag, the seams of the bag substantially or entirely include the theretofore bonded areas of the web material. As will be readily understood, this arrangement provides that the several layers of the bag will be structurally independent, except at the seams of the bag. Thus, where one of the layers of the web material used in making a bag is a heat-sealable material, the seam of the bag is formed by heat sealing along a theretofore partially heat-sealed bonding area.

An advantageous arrangement for realizing the foregoing objective is shown in FIG. 13. There, a roll 35 of loose-bonded, multi-layer web material is supported for rotation, so that the web material 36 may be drawn therefrom. The web material 36, as shown, is bonded along longitudinally extending narrow strips 37-39 at the opposite edges and along the center of the web.

As the web material 36 passes from the roll 35, it moves into a cutter or slitter 49 mounted so as to sever the web longitudinally between the lateral limits of the central bonding strip 38. The original web 36 is thus formed into two loose-bonded, multi-layer webs 41, 42 of less width, each having bonded strips along its opposite marginal edge.

After the web is severed longitudinally, the individual narrower webs may be passed to a folding and sealing station wherein the marginal edge portions are overlapped and bonded together. Thus in FIG. 13, the web 41, for example, moves through a heat sealing station comprising opposed elements 43, 44 for applying heat and pressure. The web 41 is formed into a loose-bonded, multi-layer tube, of a cross section similar to that shown in FIG. 5, and, where desired, a suitable rotary shear 45 may be provided to sever the tubes into short sections 4-6 suitable for making into bags.

It will be noted that the method and apparatus of FIG. 13 are effective to seal the web into a tube along a line which substantially entirely includes the bonded areas of the web, so that the layers of the tube are as structurally independent as is consistent with other practical considerations. The foregoing is, of course, true whether the bonding is effected by heat sealing or otherwise.

It is to be understood, of course, that the apparatus of FIG. 13 is purely illustrative, and many other arrangements may be provided for forming the webs into tubes and bags. By way of example, the web material 36, while in fiat form, may be severed into flat blanks of a size suitable for making bags, and the individual blanks may be folded and sealed to form tubular sections, such as illustrated at 46 in FIG. 13.

In FIG. 9 there is illustrated an arrangement for making a loose-bonded, multi-layer web material employing, as starting materials, a plurality of separate webs, as distinguished from the arrangement of FIG. 1, for example, where at least one of the webs is formed in an extruder during the manufacturing process. Thus, in FIG. 9, webs 47, 48 are drawn from supplies 49, brought into flat, contacting relation, and passed between rollers 14a, 53. In the illustrated apparatus, intended for use with materials adapted to be bonded by pressure or heat and pressure, the roller 14a may be similar to the roller 14 of FIG. 1, having a plurality of pressure surfaces l7a at its ends and at one or more places intermediate its ends. The roller 51 may be of cylindrical form and a of a generally non-resilient nature and, where the one of the webs 47, 48 is heat sealable, may be provided with suitable heating facilities, not specifically shown.

By way of example, the web 47 may be a material such as polyethylene, while the web 48 may be of suitable paper material. The webs are brought into contact with the heated roller 51 and then passed through the nip of rollers 14a, 51, where pressure is applied between the webs at widely spaced areas of limited size to loose-bond the webs along lines 52-54. The web material thus formed is similar to the web material 25 of FIGS. l-3, and may be formed into a roll 55 or otherwise processed.

If one of the webs 47, 48 has pressure sensitive portions, for example, the roller 51 need not be heated, and the webs need not have any dwelling contact therewith prior to passing through the nip.

In some cases, it may be desirable or expedient to form a window in the multi-layer web, as where one of the webs is opaque, the other is transparent, and it is desired to provide means for viewing through the multilayer web. In such cases, suitable openings may be 6 formed in the opaque web, the opening being covered by the transparent web in the multi-layer web. Where such windows are provided, the web forming apparatus may be provided with a roller 1412 (FIG. 8) having window-like pressure surfaces 17b of the approximate size and shape of the window. Thus, in apparatus of the type shown in FIGS. 1 and 9, for example, the roller 14b may be substituted for 14 or 14a, as the case may be, and the apparatus arranged so that the pressure surfaces 17b register with the openings in the one of the webs. Accordingly, as the webs pass through the roll nip, marginal portions of the webs surrounding the window are bonded together.

In FIG. 10, there is shown an arrangement similar to FIG. 9, but wherein a plurality of webs are secured together at widely spaced spots 56 of limited size, to form a loose-bonded, multi-layer web 57. The web is formed by drawing webs 58, 59 from supplies 60, 61, which may be rolls, bringing the webs into flat, contacting relation, and passing the webs between rollers 62, 63. If one of the webs is heat-sealable, the roller 62 may be heated, and the roller 63 is provided with a plurality of widely spaced pressure surfaces 64, of limited size, whereby loose bonding of the webs is effected. The multi-layer web material 57 may then be wound in a roll 65 or otherwise readied for subsequent use.

In the method illustrated in FIG. 11, the desired loose bonding of a plurality of webs is effected by printing or otherwise applying to one surface of one of the webs a compound which will elfectively prevent bonding of the separate webs in selected areas. By way of example, a web 66 of paper may be drawn from a supply roll 67 and passed under a gravure roller 68, or the like, whereby a compound, such as a suitable wax, is applied to one or more areas 69 which are not to be bonded. In the illustrated arrangement, compound is applied to the entire center portion of the web 66, leaving only small, widely spaced marginal edge portions exposed.

A second web 79, which may be a heat-sealable, pressure sensitive, or adhesively coated material, is drawn from a supply 71 or formed in an extruder and brought into fiat contact with the coated web 56, whereupon the webs are passed between rollers 72, 73, which apply pressure and/or heat, as the case may be. The multi-layer web 74- thus formed is of loose-bonded structure, being bonded only along the opposite marginal edges 75, 76, and may be formed into a roll 77 or otherwise used.

Another modified arrangement for forming a loosebonded, multi-layer web is shown in FIG. 12, wherein an adhesive composition is applied selectively to widely spaced areas of limited size on one or more of a plurality of webs. Thus, a web 78 is drawn from a supply 79 and passed in contact with a roller 80 adapted to apply an adhesive composition. In the illustrated apparatus, the roller applies adhesive composition to the opposite marginal edge portions of the web 78, after which the web 73 is brought into fiat contact with a second web 81, drawn from a supply 32 thereof. The webs 73, 81 may then be passed betwen rollers 83, 84, which apply pressure to bond the webs adhesively together in the manner desired, forming a loose-bonded, multi-layer web 85. The web 85 may then be formed into a roll 85, for example.

The apparatus illustrated fragmentarily in FIG. 14 is similar in most respects to the apparatus of FIG. 1, in that a first web 37 is drawn from a supply 88 thereof and passed downwardly, between rollers 89, 9% located below an extruder 91 adapted to form a web 2 or" material such as polyethylene. In this modified form of apparatus, loose bonding of the webs 87, 9-2 is effected by cooling selected surface portions of the extruded web 92 immediately prior to the passage of the webs through the nip. Thus, the roller 89 may be formed of resilient material, but in substantially cylindrical form throughout, as distinguished from the FIG. 1 apparatus, where the resilient roll has pressure surfaces 17 of increased diameter.

Cooling of the appropriate surface portion of the web 92, in the apparatus of FIG. 14, may be accomplishe by providing a plurality of air jets 93, connected to a header 94, which direct streams of cooling air onto selected portions of the web surface. Advantageously, the air streams may cool all but marginal edge portions of the web, and, perhaps, one or more intermediate areas, whereby the uncooled areas, which bond with the web 87, are widely spaced and of limited size, to form a loosebonded, multi-layer web 95 as shown at 25 in FIGS. 13.

The various methods, apparatus, and products of the invention are highly advantageous in the packaging field, where multi-layer bags and other packages are widely used. Ieretofore, the making of multi-layer bags has involved the use of complicated duplexing machines, where'm separate webs are handled and formed into packages. This involves the use of multiple web supplies, and has other disadvantages obviated by the invention, particularly in respect of the handling of certain types of webs and the obtaining of the desired structural cl aracteristics. in contrast, in accordance with the invention, a novel and improved loose-bonded, multi-layer material may be provided as an intermediate product, by a supplier, for example, and the package manufacturer may then form the end product from a single supply roll and with simplified apparatus. The end product, moreover, has improved and highly desirable characteristics of a structural and other nature.

The invention is especially useful in connection with the making of intermediate and end products of multilayer web material where one of the materials is resilient and/or non-independently handleable and/or heat-sealable. However, the invention is not limited to this extent, and may be advantageously employed with a variety of materials, in a variety of apparatus and processes, and for the manufacture of a variety of intermediate or end products. Such variations will, in view of the foregoing disclosure, readily suggest themselves to persons skilled in the art.

It should thus be understood that the various specific methods, apparatus and products herein illustrated and described are intended to be representative only, as certain departures may be made therefrom, within the clear teachings of the invention. Accordingly, reference should be made to the following appended claims in determining the full scope or" the invention.

I claim:

1. The method of making a loose-bonded multiple-wall bag, in which the multiple wall includes inner and outer layers of material, which comprises, supplying a first web of bag wall material having properties of resilience and heat-sealability, supplying a second web of bag wall material having a property of relative non-resilience in comparison to said first web of bag Wall material, bringing together said first and second Webs to superimpose one upon the other, forming a loose-bonded multiple-Wall sheet material by effecting a heat seal between said Webs over spaced areas which are very limited in relation to the total contacting area of said webs, and forming a multipie-wall, loose-bonded bag from such sheet material by folding a section of the sheet material, securing together longitudinal marginal edge portions of said sheet material and securing together marginal edge portions of said sheet material at at least one end of said portion of sheet material, whereby the multiple webs forming the walls of said bag are secured together at limited areas in relation to the total area of said walls.

2. The method of claim 1, in which said first web is supplied by extruding a web of relatively resilient heat scalable plastic material upon said second web of relatively non-resilient material and substantially immediately thereafter applying pressure to said limited areas to effect a seal.

References Cited in the file of this patent UNITED STATES PATENTS 2,125,758 Waters Aug. 2, 1938 2,169,936 Wagner Aug. 15, 1939 2,251,585 Finck Aug. 5, 1941 2,411,328 MacNab Nov. 19, 1946 2,422,725 Gilfillan June 24, 1947 2,430,459 Farrell et al Nov. 11, 1947 2,474,770 Yount et al. June 28, 1949 2,556,008 Spalding June 5, 1951 2,607,696 Kunz Aug. 19, 1952 2,714,557 Mahafiy Aug. 2, 1955. 2,714,571 Irion et al. Aug. 2, 1955 2,739,093 Bull Mar. 20, 1955 2,742,080 Cloud Apr. 17, 1956 2,749,180 Andrews June 5, 1956 2,749,817 Piazze et al June 12, 1956 2,799,211 Zerlin et al. July 16, 1957 2,805,973 Klasing et al. Sept. 10, 1957 

1. THE METHOD OF MAKING A LOOSE-BONDED MULTIPLE-WALL BAG, IN WHICH THE MULTIPLE WALL INCLUDES INNER AND OUTER LAYERS OF MATERIAL, WHICH COMPRISES, SUPPLYING A FIRST WEB OF BAG WALL MATERIAL HAVING PROPERTIES OF RESILIENCE AND HEAT-SEALABILITY, SUPPLYING A SECOND WEB OF BAG WALL MATERIAL HAVING A PROPERTY OF RELATIVE NON-RESILIENCE ON COMPARISON TO SAID FIRST WEB OF BAG WALL MATERIAL, BRINGING TOGETHER SAID FIRST AND SECOND WEBS TO SUPERIMPOSE ONE UPON THE OTHER, FORMING A LOOSE-BONDED MULTIPLE-WALL SHEET MATERIAL BY EFFECTING A HEAT SEAL BETWEEN SAID WEBS OVER SPACED AREAS WHICH ARE VERY LIMITED IN RELATION TO THE TOTAL CONTACTING AREA OF SAID WEBS, AND FORMING A MULTIPLE-WALL, LOOSE-BONDED BAG FROM SUCH SHEET MATERIAL BY FOLDING A SECTION OF THE SHEET MATERIAL, SECURING TOGETHER LONGITUDINAL MARGINAL EDGE PORTIONS OF SAID SHEET MATERIAL AND SECURING TOGETHER MARGINAL EDGE PORTIONS OF SAID SHEET MATERIAL AT AT LEAST ONE END OF SAID PORTION OF SHEET MATERIAL, WHEREBY THE MULTIPLE WEBS FORMING THE WALLS OF SAID BAG ARE SECURED TOGETHER AT LIMITED AREAS IN RELATION TO THE TOTAL AREA OF SAID WALLS. 